scholarly journals Experimental Investigation and Design Optimization of Targeted Energy Transfer Under Periodic Forcing

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Etienne Gourc ◽  
Guilhem Michon ◽  
Sébastien Seguy ◽  
Alain Berlioz
Keyword(s):  
Invariant Manifolds ◽  
Relaxation Oscillation ◽  
Design Procedure ◽  
Optimization Procedure ◽  
High Mass ◽  
Mass Ratio ◽  
Periodic Forcing ◽  
Response Curves ◽  
Mapping Procedure ◽  
Modulation Equations

In this paper, the dynamic response of a harmonically forced linear oscillator (LO) strongly coupled to a nonlinear energy sink (NES) is investigated both theoretically and experimentally. The system studied comprises an LO with an embedded, purely cubic NES. The behavior of the system is analyzed in the vicinity of 1:1 resonance. The complexification-averaging technique is used to obtain modulation equations and the associated fixed points. These modulation equations are analyzed using asymptotic expansion to study the regimes related to relaxation oscillation of the slow flow, called strongly modulated response (SMR). The zones where SMR occurs are computed using a mapping procedure. The slow invariant manifolds (SIM) are used to derive a proper optimization procedure. It is shown that there is an optimal zone in the forcing amplitude-nonlinear stiffness parameter plane, where SMR occurs without having a high amplitude detached resonance tongue. Two experimental setups are presented. One is not optimized and has a relatively high mass ratio (≈13%) and the other one is optimized and exhibits strong mass asymmetry (mass ratio ≈1%). Different frequency response curves and associated zones of SMR are obtained for various forcing amplitudes. The reported experimental results confirm the design procedure and the possible application of NES for vibration mitigation under periodic forcing.

scholarly journals Design Optimisation of a Nonlinear Energy Sink Embedded on a Harmonically Forced Linear Oscillator: Theoretical and Experimental Developments

2012 ◽  
Author(s):  
Etienne Gourc ◽  
Guilhem Michon ◽  
Sébastien Seguy ◽  
Alain Berlioz
Keyword(s):  
Invariant Manifolds ◽  
Relaxation Oscillation ◽  
Design Procedure ◽  
Nonlinear Energy Sink ◽  
Experimental Results ◽  
Linear Oscillator ◽  
Mapping Procedure ◽  
Modulation Equations ◽  
Energy Sink ◽  
Nonlinear Energy

In this paper, the dynamic response of a harmonically forced Linear Oscillator (LO) strongly coupled to a Nonlinear Energy Sink (NES) is investigated theoretically and experimentally. The system studied comprises a linear oscillator subject to an imposed displacement with an embedded, purely cubic, NES. The behavior of the system is analyzed in the vicinity of 1:1 resonance. The complexification averaging technique is used to obtain modulation equations and the associated fixed points. These modulation equations are analyzed using asymptotic expansion to study the regimes related as relaxation oscillation of the slow flow called Strongly Modulated Response (SMR). The zones where SMR occur are computed using a mapping procedure. The Slow Invariant Manifolds (SIM) is used to derive a proper optimization procedure. It is shown that there exist an optimal zone in the parameter plane forcing amplitude–nonlinear stiffness, where SMR occurs without having a high amplitude detached resonance tongue. An experimental setup exhibits a strong mass asymmetry (mass ratio ≈ 1%). The cubic stiffness is realized geometrically with two linear spring that extend axially and are free to rotate. Using the previous optimized stiffness of the NES, different frequency response curves and associated zones of SMR are obtained for various forcing amplitude. Good agreement between theoretical and experimental results is observed. The reported experimental results confirm the design procedure, and the possible application of NES for vibration mitigation under periodic forcing.

CSS J075415.6+191052 and NW Leo: two contact binaries at different evolutionary stages

2021 ◽  
Author(s):  
Xu-Dong Zhang ◽  
Shengbang Qian ◽  
Ergang Zhao ◽  
Qijun Zhi ◽  
Aijun Dong ◽  
...  
Keyword(s):  
Relaxation Oscillation ◽  
Thermal Relaxation ◽  
Light Curves ◽  
Secondary Component ◽  
High Mass ◽  
Dark Spot ◽  
Left Shoulder ◽  
Mass Ratio ◽  
Convective Envelope ◽  
Contact Binary

Abstract Multi-color light curves of CSS J075415.6+191052 and NW Leo are presented and the photometric solutions suggest that CSS J075415.6+191052 is a low mass ratio (q=0.178) and slightly deep contact binary (f=34.9%), while NW Leo with high mass ratio (q=0.707) and shallow degree of contact (f=2.3%). For CSS J075415.6+191052, the RI light curves show weakening around the left shoulder of secondary minimum, which indicates that there may be a dark spot on the secondary component. However, the light curves of BV bands are totally symmetric. It is unreasonable if the dark spot is caused by magnetic activity or mass transfers between two components. Therefore, the weakening of the light curves in this contact binary is caused by something else. A possible explanation is mass transferring from primary component to common convective envelope through the inner Lagrangian point, and this part of the mass, for some reason, weakens RI bands of light from secondary component. O - C analysis of NW Leo reveals a cyclic period change with a modulation period of 4.7 years, which may be caused by the light travel time effect of a third body. The positions of CSS J075415.6+191052 and NW Leo in P - J_{orb}' diagram suggest that the former is more evolved, which is in agreement with their photometric solutions. In the current stage, CSS J075415.6+191052 is dominated by the angular momentum loss theory, but NW Leo mainly follow the thermal relaxation oscillation theory.

The Numerical Simulation of Two-Degrees-of-Freedom Vortex-Induced Vibrations of Circular Cylinder with High Mass-Ratio

2013 ◽  
Vol 284-287 ◽  
pp. 557-561
Author(s):  
Jie Li Fan ◽  
Wei Ping Huang
Keyword(s):  
Circular Cylinder ◽  
Drag Force ◽  
Frequency Ratio ◽  
Lift Force ◽  
Degrees Of Freedom ◽  
Cross Flow ◽  
High Mass ◽  
Mass Ratio ◽  
Main Frequency ◽  
Line Amplitude

The two-degrees-of-freedom VIV of the circular cylinder with high mass-ratio is numerically simulated with the software ANSYS/CFX. The VIV characteristic is analyzed in the different conditions (Ur=3, 5, 6, 8, 10). When Ur is 5, 6, 8 and 10, the conclusion which is different from the cylinder with low mass-ratio can be obtained. When Ur is 3, the frequency of in-line VIV is twice of that of cross-flow VIV which is equal to the frequency ratio between drag force and lift force, and the in-line amplitude is much smaller than the cross-flow amplitude. The motion trace is the crescent. When Ur is 5 and 6, the frequency ratio between the drag force and lift force is still 2, but the main frequency of in-line VIV is mainly the same as that of cross-flow VIV and the secondary frequency of in-line VIV is equal to the frequency of the drag force. The in-line amplitude is still very small compared with the cross-flow amplitude. When Ur is up to 8 and 10, the frequency of in-line VIV is the same as the main frequency of cross-flow VIV which is close to the inherent frequency of the cylinder and is different from the frequency of drag force or lift force. But the secondary frequency of cross-flow VIV is equal to the frequency of the lift force. The amplitude ratio of the VIV between in-line and cross-flow direction is about 0.5. When Ur is 5, 6, 8 and 10, the motion trace is mainly the oval.

Optimization of Turbofan Propulsion Cycle Using a Genetic Algorithm

2010 ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
Genetic Algorithm ◽  
Fuel Consumption ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Optimization Procedure ◽  
Specific Fuel Consumption ◽  
High Mass ◽  
Design Parameters ◽  
Inlet Temperature ◽  
Simplifying Assumptions

This paper presents an evolutionary approach as the optimization framework to design for the optimal performance of a high-bypass unmixed turbofan to match with the power requirements of a commercial aircraft. The parametric analysis had the objective to highlight the effects of the principal design parameters on the propulsive performance in terms of specific fuel consumption and specific thrust. The design optimization procedure based on the genetic algorithm PIKAIA coupled to the developed engine performance analyzer (on-design and off-design) aimed at finding the propulsion cycle parameters minimizing the specific fuel consumption, while meeting the required thrusts in cruise and takeoff and the restrictions of temperatures limits, engine size and weight as well as pollutants emissions. This methodology does not use engine components’ maps and operates on simplifying assumptions which are satisfying the conceptual or early design stages. The predefined requirements and design constraints have resulted in an engine with high mass flow rate, bypass ratio and overall pressure ratio and a moderate turbine inlet temperature. In general, the optimized engine is fairly comparable with available engines of equivalent power range.

scholarly journals A New Design Procedure for Rotor Laminations of Synchronous Reluctance Machines with Fluid Shaped Barriers

Electronics ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 134
Author(s):  
Federica Uberti ◽  
Lucia Frosini ◽  
Loránd Szabó
Keyword(s):  
Finite Element ◽  
Design Procedure ◽  
Optimization Procedure ◽  
Torque Ripple ◽  
Stator Winding ◽  
Post Processing ◽  
Processing Stage ◽  
Synchronous Reluctance Machine ◽  
Design And Optimization ◽  
Reluctance Machine

A new procedure for the design and optimization of the rotor laminations of a synchronous reluctance machine is presented in this paper. The configuration of the laminations is symmetrical and contains fluid-shaped barriers. The parametrization principle is used, which executes variations in the lamination geometry by changing the position, thickness and shape of the flux barriers. Hence, the optimization procedure analyzes the various configurations through finite element simulations, by means of the communication between MATLAB and Flux 2D. In the post processing stage, the best geometry which optimizes mean torque, torque ripple, efficiency and power factor is selected. Once the best rotor configuration is defined, further investigations allow improving its performance by modifying the current angle, the stator winding and the thickness of the radial ribs.

scholarly journals A photometric study of the high-mass-ratio contact binary AV Puppis

2019 ◽  
Vol 19 (12) ◽  
pp. 174 ◽  
Author(s):  
Quan-Wang Han ◽  
Li-Fang Li ◽  
Deng-Kai Jiang
Keyword(s):  
High Mass ◽  
Photometric Study ◽  
Mass Ratio ◽  
Contact Binary

scholarly journals High Mass Ratio Contact Binaries: Recent Evolution into Contact?

1989 ◽  
Vol 107 ◽  
pp. 348-349
Author(s):  
Bruce J. Hrivnak
Keyword(s):  
Mass Transfer ◽  
Angular Momentum ◽  
Primary Component ◽  
High Mass ◽  
Mass Ratio ◽  
Origin And Evolution ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
Mass Ratios ◽  
Contact Binaries

Recent theories of the origin and evolution of contact binaries suggest that the two stars evolve into contact through angular momentum loss (AML; Mochnacki 1981, Vilhu 1982). When in contact, the system then evolves toward smaller mass ratio through mass transfer from the secondary to the primary component (Webbink 1976, Rahunen and Vilhu 1982). Most contact binaries have mass ratios of 0.3 to 0.5.

scholarly journals A Comprehensive Membrane Process for Preparing Lithium Carbonate from High Mg/Li Brine

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 371
Author(s):  
Wenhua Xu ◽  
Dongfu Liu ◽  
Lihua He ◽  
Zhongwei Zhao
Keyword(s):  
Reverse Osmosis ◽  
Membrane Separation ◽  
Lithium Carbonate ◽  
High Mass ◽  
Separation Performance ◽  
Mass Ratio ◽  
Total Recovery ◽  
Industrial Grade ◽  
Electrochemical Intercalation ◽  
New Perspective

The preparation of Li2CO3 from brine with a high mass ratio of Mg/Li is a worldwide technology problem. Membrane separation is considered as a green and efficient method. In this paper, a comprehensive Li2CO3 preparation process, which involves electrochemical intercalation-deintercalation, nanofiltration, reverse osmosis, evaporation, and precipitation, was constructed. Concretely, the electrochemical intercalation-deintercalation method shows excellent separation performance of lithium and magnesium, and the mass ratio of Mg/Li decreased from the initial 58.5 in the brine to 0.93 in the obtained lithium-containing anolyte. Subsequently, the purification and concentration are performed based on nanofiltration and reverse osmosis technologies, which remove mass magnesium and enrich lithium, respectively. After further evaporation and purification, industrial-grade Li2CO3 can be prepared directly. The direct recovery of lithium from the high Mg/Li brine to the production of Li2CO3 can reach 68.7%, considering that most of the solutions are cycled in the system, the total recovery of lithium will be greater than 85%. In general, this new integrated lithium extraction system provides a new perspective for preparing lithium carbonate from high Mg/Li brine.

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